> We live in a world full of potential dangers (lots in my world, and lots
of close calls)--please be realistic!
You are right, Randy, I'm a dreamer. That's even the reason I love bees and
flowers. So, in this world, it's my duty to love facts too. Here are some.
Let's talk about 'sub-lethal', for instance.
"This study is the first to demonstrate sub-lethal effects on worker honey
bees from pesticide residue exposure from contaminated brood comb.
Sub-lethal effects, including delayed larval development and adult emergence
or shortened adult longevity, can have indirect effects on the colony such
as premature shifts in hive roles and foraging activity. In addition, longer
development time for bees may provide a reproductive advantage for parasitic
Varroa destructor mites. The impact of delayed development in bees on Varroa
mite fecundity should be examined further.
"Sub-lethal Effects of Pesticide Residues in Brood Comb on Worker Honey Bee
(Apis mellifera) Development and Longevity", Judy Wu, Carol Anelli, Walter
Sheppard. Plos One, feb. 23, 2011.
And about the difference between 'Acute' and 'chronic'.
"Imidaclopridi a systemic nitroguanidine insecticide that belongs to
theneonicotinoid family. As an agonist of the acetylcholine receptor, it
attacks the insect nervous system and is extremely effective against various
sucking and mining pests. Oral acute and chronic toxicity of imidacloprid
and its main metabolites (5-hydroxyimidacloprid, 4,5-dihydroxyimidacloprid,
desnitroimidacloprid, 6-chloronicotinic acid, olefin, and urea derivative)
were investigated in Apis mellifera. Acute intoxication by imidacloprid or
its metabolites resulted in the rapid appearance of neurotoxicity symptoms,
such as hyperresponsiveness, hyperactivity, and trembling and led to
hyporesponsiveness and hypoactivity. For acute toxicity tests, bees were
treated with doses of toxic compounds ranging from 1 to 1,000 ng/bee (10¨C
10,000 ¦Ìg/kg). Acute toxicity (LD50) values of imidacloprid were about 60
ng/bee (600 ¦Ìg/kg) at 48 h and about 40 ng/bee (400 ¦Ìg/kg) at 72 and 96 h.
Out of the six imidacloprid metabolites tested, only two
(5-hydroxyimidacloprid and olefin) exhibited a toxicity close to that of
imidacloprid. Olefin LD50 values were lower than those of imidacloprid. The
5-hydroxyimidacloprid showed a lower toxicity than imidacloprid with a LD50
four to six times higher than that of imidacloprid. Urea also appeared as a
compound of nonnegligible toxicity by eliciting close to 40% mortality at 1,
000 ng/bee (10,000 ¦Ìg/kg). However, no significant toxicity was observed
with 4,5-dihydroxyimidacloprid, 6-chloronicotinic acid, and
desnitroimidacloprid in the range of doses tested. To test chronic toxicity,
worker bees were fed sucrose solutions containing 0.1, 1, and 10 ¦Ìg/L of
imidacloprid and its metabolites for 10 d. Fifty percent mortality was
reached at approximately 8 d. Hence, considering that sucrose syrup was
consumed at the mean rate of 12 ¦Ìl/d and per bee, after an 8-d period the
cumulated doses were approximately 0.01, 0.1, and 1 ng/bee (0.1, 1, and 10
¦Ìg/kg). Thus, all tested compounds were toxic at doses 30 to 3,000
(olefin), 60 to 6,000 (imidacloprid), 200 to 20,000 (5-OH-imidacloprid), and
>1,000 to 100,000 (remaining metabolites) times lower than those required to
produce the same effect in acute intoxication studies. For all products
tested, bee mortality was induced only 72 h after the onset of intoxication.
"
"Discrepancy between acute and chronic toxicity induced by imidacloprid and
its metabolites in Apis mellifera"
S¨¦verine Suchail, David Guez, Luc P. Belzunces*, Article first published
online: 3 NOV 2009.
And further on:
http://scholar.google.be/scholar?hl=fr&as_sdt=0,5&q=apis+mellifera+chronic+t
oxicity+imidacloprid
Kind regards,
Ghislain De Roeck,
Belgium.
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